The present invention relates to a damper disc used as a clutch disc of automobiles, or the like.
A structure in FIG. 1 has already been proposed as a damper disc having a large torsion angle and stepped torsion characteristic. In FIG. 1, a spline hub 1 and an annular flange 2 there-around are separated from each other, and are adapted to be unrotatably connected by radial claws or teeth 3 and 4. A pair of sub-plates 5 are disposed at opposite sides of the flange 2. Although they are not shown, side plates which are a clutch plate and a retaining plate are disposed at opposite sides of the sub-plates 5. The sub-plates 5 are rigidly connected to the flange 2 by sub-pins 6, and are connected to the hub 1 through weak torsion springs 9. The flange 2 are connected to the side plates through strong torsion springs 8.
According to this structure, when a transmitted torque is small (section 0-a in FIG. 2), the weak springs 9 are compressed. After the transmitted torque and the torsion angle increase to values of Ta and .theta.a respectively, and the teeth 3 and 4 contact with each other, the springs 8 are compressed. Therefore, the transmitted torque-torsion angle characteristic is determined as shown in FIG. 2 and is stepped and has a large torsion angle, so that an absorbing effect for torque vibration is improved.
However, according to the above structure, noises may be generated when the teeth 3 and 4 collide with each other. Since the teeth 3 and 4 project radially from the outer periphery of the hub 1 and the inner periphery of the flange 2, respectively, the teeth 3 and 4 may break when they collide with each other. Especially, in such cases that a space S between the teeth 3 and 4 and/or openings for the springs 9 are determined long in order to increase the maximim torsion angle, the strength of the teeth 3 and 4 is remarkably reduced.
Accordingly, it is an object of the invention to provide an improved damper disc, overcoming the above-noted disadvantages.
The essence of the invention is to provide a radial flange formed integrally with a spline hub and a pair of subplates which are designed to torsionally turn or twist together with side plates with respect to the flange when a torsion angle is small.
Other and further objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiments of the invention.